The current marketplace for work machines, and particularly agricultural machines such as combine harvesters, is substantially driven by advertised horsepower. To keep pace with competition, manufacturers have been substantially increasing available engine power. This peak torque power of the specified engine is required to operate the full complement of product applications and variations. For instance, a combine can be used with a variety of different header configurations, e.g., corn (maize), or small grain (wheat, legumes), which headers can be of vastly different widths, and thus have widely different power requirements. For satisfactory performance, the engine of such a combine harvester has to provide power to each and every crop processing subsystem and the top range combine harvesters have engines that can readily provide the needed power in all modes of operation.
In a combine harvester, the rotating threshing drum or rotor of the threshing mechanism is the greatest power consumer. Residue chopping also requires a substantial amount of power, especially when chopping straw of small grain crops, such as wheat and barley. Thus, when the chopper is configured in the chopping mode, an adequate, relatively large amount of engine power must be available, both for operating the chopper under normal loads, and also when heavier loads are present, such as when a slug of crop residue is processed. This power requirement may vary, however, within a wide range, as a function of the operating speed, and the position of counter or stationary knives of the chopper. In other instances, particularly when it is desired to windrow or swath the crop residue, the straw chopper is bypassed, e.g., by positioning of doors or plates, and may be idle, and even disengaged entirely from the engine. As a further possible configuration, even though the chopper is not configured for chopping, the chopper may still require some amount of available engine power, for instance, as a result of being unintentionally being left running or engaged even though mechanically bypassed, or because of being intentionally left running while bypassed so as to chop any crop residue that still makes it into the chopper, to avoid clogging the chopper. And, as a further possible configuration, the crop residue may be directed to bypass the chopper and instead enter a crop residue spreader, so as to substantially increase the power demand of that device. Each of these configurations will have its own required power level that will be less than the full amount of power that the engine is able to direct to the subsystems, such that if available maximum power is not properly managed for a given configuration, damage can result. And, conversely, if insufficient maximum power is available, performance can suffer.
To explain, when such a substantial power consuming subsystem as the straw chopper is bypassed or disengaged, more power becomes available for the other crop processing subsystems. The spare engine capacity can increase the power applied to other subsystems, such as the driveline of the threshing drum of the threshing or separating apparatus. The operator, who often wants to maximize on harvesting capacity, may tend to use the spare power to accelerate the combine harvester, in order the increase the machine throughput. By doing so, however, an operator risks exceeding a subsystem's capacity. For example, threshing efficiency typically decreases drastically if too much crop is taken in. Overload will eventually result in excessive wear/and or deformation of the components of the crop processing subsystem. Elements of the threshing system, such as threshing slats, may bend and threshing concaves may become distorted. The available amount of power may also exceed the mechanical limitations of the driveline to the threshing drum, thereby shortening the lifetime of components such as drive belts and gearboxes. Thus, it is apparent that it would be desirable to have a scheme or system for more closely or precisely controlling available engine power, under a wide range of possible crop handling or processing subsystem configurations.
Manufacturers have devised a variety of engine power management systems and schemes for combine harvesters. Reference generally, Heisey, U.S. Pat. No. 6,865,870, issued Mar. 15, 2005 to CNH America LLC, which provides a system that provides different overall power levels for different operating modes, e.g., field work verses road travel. There are also known systems that set power levels as a function of equipment connected to the harvester. Several such systems utilize detectors for determining the identity of a header attached to a combine harvester, and provide corresponding stored engine power curves for the particular headers. Reference in this regard, Ehrecke, U.S. Pat. No. 6,397,571, issued Jun. 4, 2002 to Deere and Company. Manufacturers have also devised engine power management schemes for setting available engine power levels as a function of systems of the machine that are currently engaged or operating, e.g., straw chopper, propulsion system, harvester assembly, separator, as indicated by the positions of switches for engaging or activating the respective systems, e.g., the on/off switches for the systems. Reference in this regard, Wyffels, U.S. Pat. No. 5,878,557, issued Mar. 9, 1999 to Deere and Company. Still other engine management schemes rely on sensed measurements of actual power usage of the various systems, for determining available power level values. Reference in this regard, Dickhaus, U.S. Pat. No. 6,073,428, issued Jun. 13, 2000 to Claas Selbstfahrende Erntemaschinen GmbH.
However, an observed shortcoming of setting maximum available power as a function of overall operating mode as suggested above in the first patent, and based on header identity alone, such as proposed in U.S. Pat. No. 6,397,571, is that too much available power may be present in instances when less than all crop processing subsystems are engaged. As noted above, these subsystems often are significant contributors to the total consumed power. In removing the power requirements of one or more of the major subsystems, i.e., turning off or disengaging some of the systems, the balance of subsystems still on or engaged can divide the total available power. In many cases, however, this can result in substantially overrunning the subsystems' functional capability, resulting in grain loss, etc., or exceeding mechanical limits causing failures. It is not cost effective to design every system to carry the maximum available power for a plethora of configurations, but rather it would be preferred to limit available power to the subsystem not exceeding its performance limits.
Setting maximum available power based on the identity of engaged or activated subsystems such as by monitoring on/off switches as proposed in U.S. Pat. No. 5,878,557, also suffers from a shortcoming that practically, it will necessitate setting the available power level to accommodate the maximum expected power usage of those subsystems, and doesn't accommodate reduced power needs of different configurations of the subsystems. For example, as set forth above, an engaged straw chopper may use as little as just a few horsepower. For instance, a chopper may use as little as 20 horsepower, if configured one way, e.g., bypassed and idling, and as much as 150 horsepower if configured another way, e.g., for receiving straw and with stationary knives fully extended or deployed. Thus, this system falls short of providing a closely tailored level of available power for different subsystem configurations having different power needs.
Setting maximum available power as a function of measured actual usage, as proposed in U.S. Pat. No. 6,073,428, suffers from the shortcoming that it must rely on measurement means that can be unreliable, inaccurate, and/or complex, and can require calibration to ensure accuracy, so as to be of limited practicality. Also, the actual power usage can vary significantly during operation as a result of temporary or intermittent operating conditions such as passage of slugs of crop material through the crop processing systems, such that the level of available power will be correspondingly varied, reactive to demand, as opposed to in anticipation of demand, which can be problematic. For example, if the actual power usage during an interval of time is relatively low as a result of smooth operating conditions, the available maximum engine power may be set to reflect this. But, when an abrupt increase in power demand occurs, such as entry of a slug of dense crop material into one or more of the crop processing subsystems, e.g., the threshing system, chopper, or spreader, the additional engine power available may be inadequate. This inadequate power can cause the engine to bog down or stall, such that other subsystem performance suffers. Then, if in response the system automatically or the operator manually increases power, after the need for the additional power has passed, the now available power will not closely match actual power needs.
Thus, what is sought is a control operable for setting a level of maximum engine power available for any given product derivation, configuration or mode, including wherein one or more subsystems of a combine may not be being used, or is configured in any of a variety of relatively low power requirement options verses a higher power requirement option, which control is not reliant on power usage measurement means which may suffer from the shortcomings and disadvantages set forth above.